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Discussion Starter · #1 · (Edited)
Hi all. A little while back my timing chain tensioner failed while I had the car on blocks for a few weeks while I worked on a clutch replacement. This allowed my motor to lose its timing and it would no longer run, but it took me another week of troubleshooting to figure out what was going on. In that time I probably turned the motor over about 100 times using the starter motor while I was trying to troubleshoot, but at no point when the motor was out of time did it run on its own power. At this point I decided to tow the car off to a shop to get a professional opinion (the first and last time I'll ever send this car to a shop). After a week and $300 in flat towing costs they told me they scoped the motor, found evidence of valve/piston damage, and that the car wasn't worth working on due to its mileage. Ok, fair enough, I got the car back in the garage and figured I had nothing to lose so I ordered myself an engine hoist. Today I finally got the head off of the block to take a look inside to see the damage and now I'm confused. See the pictures below. Either I don't know what I'm looking for here, or the shop I went to did less than nothing and took my money when they decided my car wasn't worth working on. At this point I'm about to put the motor back together, get the timing sorted out, and check compression but I wanted to get some feedback from folks here first.

Long story short, do the pictures below show any indication of piston or valve damage? Is there anything else I should be looking out for?
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I believe the timing chain engines are not interference engines,someone correct me if im wrong.
No worries dusterdude but I believe quite the opposite. Virtually all automotive engines today are interference engines. They are lighter and more compact and are therefore more efficient. Fortunately, Honda uses timing chains instead of timing belts and they are supposed to last much longer and rarely if ever break but I have no hard evidence of this yet I believe this to be true. Here is a list of Interference and Non-interference engines. I cannot verify the accuracy of the list I linked to.

Did the shop take off the head? If not, how in the hell did they scope the engine. Through the spark plug hole? Seriously, how much can you see that way. Did they show you evidence of their findings. From your pictures, I see no evidence of piston contact with valve. If there was, you would see scarring on the pistons and I don't see any there or on the valves either. There is some carbon build up but I think this is normal and not a real big deal. Pistons, rings, valves and valve seats are much harder than carbon residue. If any breaks off it should just be blown out the exhaust.

I do see something on this image in the upper right along the outer edge but I can't tell what it is. You should check it out. https://www.8thcivic.com/attachments/20221120_144953_hdr-jpg.247452/

What I do not see is any clear evidence of pistons and valves crashing. Investigating this further would involve checking the connecting rods for any damage especially if they are aluminum. Aluminum does not spring back and a damaged aluminum rod will almost certainly fail at some point with catastrophic results like a big hole in your block. Crank shaft would need to be checked for straightness and any damage to the journals. This requires someone who has the right tools and knows what they are doing. I know of good crank machinists in Michigan if you are anywhere near by. Not sure if they do Hondas but I don't see why not. Not sure how valves are checked for being bent. If problems were found a full valve job might be in order. New valves, springs, guides, and machining valve seats. All this requires highly specialized expensive machines. Serdi is a top brand. If no problems were found, cylinders should probably be honed and pistons re-ringed.

So, maybe at low revs, no damage was done. So there you have it. If it was mine, I would probably slap it together and go for it. Worse that can happen is you end having to buy a used engine, maybe a low mileage JDM engine. Doing all the work I described would probably cost much more. Up to you though. And remember, I am just a self-educated shade tree mechanic. ;)

Proceed with caution. A seized engine is serious.

HTH
 

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Discussion Starter · #4 · (Edited)
No worries dusterdude but I believe quite the opposite. Virtually all automotive engines today are interference engines. They are lighter and more compact and are therefore more efficient. Fortunately, Honda uses timing chains instead of timing belts and they are supposed to last much longer and rarely if ever break but I have no hard evidence of this yet I believe this to be true. Here is a list of Interference and Non-interference engines. I cannot verify the accuracy of the list I linked to.

Did the shop take off the head? If not, how in the hell did they scope the engine. Through the spark plug hole? Seriously, how much can you see that way. Did they show you evidence of their findings. From your pictures, I see no evidence of piston contact with valve. If there was, you would see scarring on the pistons and I don't see any there or on the valves either. There is some carbon build up but I think this is normal and not a real big deal. Pistons, rings, valves and valve seats are much harder than carbon residue. If any breaks off it should just be blown out the exhaust.

I do see something on this image in the upper right along the outer edge but I can't tell what it is. You should check it out. https://www.8thcivic.com/attachments/20221120_144953_hdr-jpg.247452/

What I do not see is any clear evidence of pistons and valves crashing. Investigating this further would involve checking the connecting rods for any damage especially if they are aluminum. Aluminum does not spring back and a damaged aluminum rod will almost certainly fail at some point with catastrophic results like a big hole in your block. Crank shaft would need to be checked for straightness and any damage to the journals. This requires someone who has the right tools and knows what they are doing. I know of good crank machinists in Michigan if you are anywhere near by. Not sure if they do Hondas but I don't see why not. Not sure how valves are checked for being bent. If problems were found a full valve job might be in order. New valves, springs, guides, and machining valve seats. All this requires highly specialized expensive machines. Serdi is a top brand. If no problems were found, cylinders should probably be honed and pistons re-ringed.

So, maybe at low revs, no damage was done. So there you have it. If it was mine, I would probably slap it together and go for it. Worse that can happen is you end having to buy a used engine, maybe a low mileage JDM engine. Doing all the work I described would probably cost much more. Up to you though. And remember, I am just a self-educated shade tree mechanic. ;)

Proceed with caution. A seized engine is serious.

HTH
Thanks so much for the reply. No, the shop definitely didn't pull the head. They claimed they just scoped through the spark plug hole, but I'm dubious if they even did that much at this point. I think at this point I'm just going to re-assemble and test my compression and go from there.
 

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Are the cams still in the head? If so I'd put a wrench on the bolts holding the cam sprockets to rotate the cams, while looking at the valves as they open close to see if any are bent. I don't think you can really determine much with the valves fully closed. Otherwise you could remove the valves and inspect them individually by rolling the stem on a flat surface.
That said, from you pictures I personally don't see any indication of contact. There's a channel on ytube called "I Do Cars" where he tears down wrecked engines, and from what I've seen there, it's very obvious when there's been interference. "Malice in the combustion palace" as he says.
 

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Examined the photos and did not find any sign of marks on either valves or pistons. I would assemble the engine, perform a compression test and run the engine.
Then drive the car to the service place, show them the photos and the car and demand your money back.
Let us know the end.
 

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It is an interference motor you can have piston to valve contact 100% on these motors. That's why some people clay their motors when doing a build to see the max vtc they can run. I feel it in taking your car to garages every garage I've taken my car to had messed something up. The shop that did my k24a2 swap messed a bunch of crap up including breaking like 4 bolts on my oil pan as I had then swap the z3 pan over was it's better than the a2 pan and the bolts are broke and they didn't bother fixing it and that's after they took days fixing other "broken bolts" I'm not even going to get into the rest because they ruined everything they touched like leaving sensors unplugged, not putting the wheel well back on, tearing my center consol apart to put in shifting cables and then claming they can't add they didn't have the tools to do so even though my carpet was all pushed back etc. The other shop left my alignment undone and didn't even try to get it close after getting a clutch done amount not tightening my tie rod so on the way home when I turned left something clunked really bad and my clutch still doesn't fully disengage which is why I took the car their to have a new clutch put in and then they said with the new clutch the issue was now gone and I got in my car and sure enough it wasn't. People don't like working on 8th gens because it's a tight setup to work on but any garage that said that is just lazy as its your money and if you want it done they should of done it I mean I get warning you but if you said I still want it done and they didn't want to its because they are lazy so I wouldn't go back there. As far as piston to valve contact I think the damage would be on the stem on the valve not the head of the valve but if you get a bore scope or have someone else bore scope it and there's no damage I would take pics and get your money back. If there's one thing I've learned over the years is if you take your car to a garage you always look over it after to make sure they did what they said they did and make sure everything is good and they didn't leave anything lose etc. There's tons of shops that pull scams like changing spark plugs etc and bill you for labor and parts and don't do anything. I've seen many videos of people taking their car to a garage and they claim they need a tune up or new ignition coils etc and then charge them for it and when they take their car to a backyard mechanic they notice none of that stuff was changed. Most shops think people won't take their car apart and look to make sure do always go over their work ya know. As far as the motor goes out would be cheaper to rebuild your z3 then buy one as z3s with 100k miles are going for like 2-3k however the cheapest option would be to go k24 as you can find then on eBay with 50k miles for 800$ if you wanted to get the most bang for your buck is get that and then have your z3 head rebuilt with upgraded valve train and have hit a Frankenstein built. A k24 will swap right in for the most part. Interswappable parts too pretty much as well
 

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I would take the head for a valve job while you have it off. Get new valve stem seals of course. The shop has a vacuum table and can pull vacuum to see if the valves are leaking, but I'd just go ahead and have the valve job. Any bent valve will show up immediately. Also, depending on how you removed the head (unbolting sequence), a good time to get it checked that it isn't warped. If it is, a light mill to clean it up. Put it back together with ARP head studs. Reusing the head bolts is a no-no, as they were originally stretched during the factory build. Next, buy new cam and oil chain sets, with new tensioners and guides. And buy a timing chain guide to add protection from the timing chain ever slipping off the crank sprocket in the future. It's difficult to do all this in the car, but it can be done. Hopefully, you have a good Honda (factory) service manual to guide you. Buy the head gasket from Honda. You can buy the chains, etc., from RockAuto and be okay if you stick to the high end ones (price). The manual will show how to time the engine and the cams correctly. Follow it carefully. Torque sequence of head (studs) and lifter assemblies is critical. Best of luck. Come back to the forum and ask any questions you might have. BTW, my engine is a 2011 K20Z3, and I have completely rebuilt it once.
 

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Thanks so much for the reply. No, the shop definitely didn't pull the head. They claimed they just scoped through the spark plug hole, but I'm dubious if they even did that much at this point. I think at this point I'm just going to re-assemble and test my compression and go from there.
while you have the head off , set it up on bench and pour some kerosene or similar in the combustion chamber look & see if it leaks past the valves this can tell you if they were hit &not seating (rather than trouble of re-assemble & compression ck. to find out they were'nt sealing either) I can't see a hit mark & usually you can. take 1 thing at a time & don't worry about con rods or crank. I have the factory manual in front of me & can't find if it addresses interference or not . it does go into a pretty thorough valve inspection (seating stem dia. etc) just see if they are sealing first. mark on piston is usually see-able
 

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while you have the head off , set it up on bench and pour some kerosene or similar in the combustion chamber look & see if it leaks past the valves this can tell you if they were hit &not seating (rather than trouble of re-assemble & compression ck. to find out they were'nt sealing either) I can't see a hit mark & usually you can. take 1 thing at a time & don't worry about con rods or crank. I have the factory manual in front of me & can't find if it addresses interference or not . it does go into a pretty thorough valve inspection (seating stem dia. etc) just see if they are sealing first. mark on piston is usually see-able
you were working on the clutch, & then the motor wouldn't start? you know there is a switch on clutch pedal that stops the motor from starting if the pedal is not depressed (with the switch in adjustment ?) you turned motor over 100 times without firing .
 
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